GI Drugs

Question 1

How do you treat ulcers?

Answer 1

H2 antagonists + PPIs
Antibiotics for H.Pylori

Question 2

What releases gastric acid?

Answer 2

Parietal cells

Question 3

How is gastric acid released?
Brief explanation

Answer 3

Promoted by Ach, gastrin + histamine
Histamine stimulates gastric acid release by H2 receptor

Question 4

What is H1 responsible for?

Answer 4

Classical actions of histamine

Question 5

What is H2 responsible for?

Answer 5

Receptor on parietal cells

Question 6

What is require for H1 + H2 agonism?

Answer 6

H1 = 2 N group
H2 = 3 N groups = need 3 interactions

Question 7

What is the drug doing?

Answer 7

Preventing from histamine binding

Question 8

What is guanidine group?

Answer 8

Basic + ionised at physiological pH

Question 9

What can you do when antagonist binding site is far away?

Answer 9

Extend the chain

Question 10

What is a partial agonist?

Answer 10

Binds as agonist in one mode + antagonist in other

Question 11

What is thiourea?

Answer 11

Weak antagonist + not an agonist

Question 12

What is a reason (chemistry) that it is more potent?

Answer 12

Reach antagonist region

Question 13

What does it mean if it doesn’t have oral efficacy?

Answer 13

Can’t be taken as a tablet

Question 14

Why methyl group added?

Answer 14

e- donating

Question 15

Why may there have been increased activity?

Answer 15

Conformational effect
Flexibility increased
Methyl added = creating conformational effect

Question 16

Describe cimetidine

Answer 16

Comparable efficacy
Improved side effect profile
H2 receptor antagonists

Question 17

What do proton pumps do?

Answer 17

Pump H+ out of parietal cell + K+ back in
Requires energy from hydrolysis of ATP - ADP

Question 18

What do PPIs act as?

Answer 18

Prodrugs activated by strong acidic conditions

Question 19

Describe mechanism of inhibition

Answer 19

Activated compound = H2O added
Proton pump attacks sulphur + forms irreversible bond
Drug activated by acid